Video surveillance technology has advanced substantially over the past few years. Many video surveillance systems have adopted digital imaging, recording and processing technologies in an attempt to more efficiently record, process, search and access video information.
The use of digital imaging, recording and processing technologies has been a key enabler for adapting video surveillance systems to further include networking and remote access capabilities. Video surveillance systems with networking and remote access capabilities are referred to as networked video surveillance systems hereinafter.
Typically, a conventional network modem is used to add networking and remote access capabilities to a piece of surveillance equipment. The inclusion of a conventional network modem permits a particular piece of surveillance equipment to be treated as a network node. Conventional network modems are limited to particular communication technologies such as telephony, cable, CAT5 Ethernet, and various wireless networks. Each of these conventional communication technologies requires access to a corresponding specific type of communication channel in addition to a power supply system required to energize a particular modem. Consequently, deployment of a networked video surveillance system is limited to those areas that have access to a specific type of requisite communication channel. Moreover, each access method has merits and drawbacks that make each access method preferable for some applications and not others.
A dedicated wired network, such as CAT5 Ethernet, is preferable for applications requiring high bandwidth and high video quality. A location that does not have a requisite network connection must be retro-fitted to include the necessary wiring. New wire installation is costly and wired networks cannot be conveniently redeployed as network nodes are considered fixed as a result of their wired network connection. In some cases (e.g. home networking), new wire installation and/or repositioning of existing wiring is not welcome for a variety of reasons that include inconvenience, esthetics and additional cost.
Networking over shared telephony lines is a related alternative. However, as for dedicated wired networks, a surveillance location must have a telephone connection or be retro-fitted to include one. Thus, the deployment of a video surveillance system employing telephony lines still requires the existence of a respective network connection for each surveillance location.
Wireless networks are somewhat more flexible than wired networks. However, wireless networks do have a number of drawbacks that include issues relating to system security and low levels of received signal strength relating to the location of a wireless modem.
In particular, wireless networks are sometimes limited by signal propagation through certain spaces that may prevent a wireless signal from being transmitted or received from a particular geographic location. For example, in some instances it is difficult to set up a wireless link to a particular location within a building (e.g. inside an elevator, an underground parking garage, etc.) from another location inside or outside the same building. Thus, video surveillance of a location is sometimes not possible using a wireless link since the received signal strength is not high enough to enable demodulation and decoding of video information carried on a respective wireless signal.
With respect to security issues, wireless networks are susceptible to eavesdropping and other forms of interference, including jamming. These issues, if not adequately addressed, allow a system to be easily compromised. This is highly undesirable because video surveillance systems are often employed in security and privacy sensitive applications.